This core is an endocrinology core designed to measure two aspects of neuroendocrine responses that are known to impact on immune responses, and particularly to impact those immune responses involved in healing: the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic adrenal medullary (SAM) axis. HPA axis hormones to be assessed will be plasma and salivary cortisol, plasma ACTH, DHEA and its metabolites. SAM mediators measured will be plasma catecholamines epinephrine and norepinephrine. Other hormones measured will be pituitary growth hormone and IGF-1.